JMeter Graphite Backend Listener throws exception when test ends

and useRegexpForSamplersList is set to true.
Based on patch by Liu XP (liu_xp2003 at sina.com)

Bugzilla Id: 60428


git-svn-id: https://svn.apache.org/repos/asf/jmeter/trunk@1771952 13f79535-47bb-0310-9956-ffa450edef68

Former-commit-id: 1a488f683e

src/components/org/apache/jmeter/visualizers/backend/graphite/GraphiteBackendListenerClient.java

@@ -323,8 +323,10 @@ public class GraphiteBackendListenerClient extends AbstractBackendListenerClient
         }
         // Send last set of data before ending
         sendMetrics();
-        
-        samplersToFilter.clear();
+
+        if (samplersToFilter != null) {
+            samplersToFilter.clear();
+        }
         graphiteMetricsManager.destroy();
         super.teardownTest(context);
     }

xdocs/changes.xml

@@ -180,6 +180,9 @@ Fill in some detail.
 
 <h3>General</h3>
 <ul>
+    <li><bug>60428</bug>JMeter Graphite Backend Listener throws exception when test ends
+    and <code>useRegexpForSamplersList</code> is set to <code>true</code>.
+    Based on patch by Liu XP (liu_xp2003 at sina.com)</li>
 </ul>
 
  <!--  =================== Thanks =================== -->
@@ -189,6 +192,7 @@ Fill in some detail.
 </p>
 <ul>
 <li>Jerome Loisel (loisel.jerome at gmail.com)</li>
+<li>Liu XP (liu_xp2003 at sina.com)</li>
 </ul>
 <p>We also thank bug reporters who helped us improve JMeter. <br/>
 For this release we want to give special thanks to the following reporters for the clear reports and tests made after our fixes:</p>